Emergence of 4-D System Fundamental Diagram in Urban Air Mobility Traffic Flow

2021 ◽  
pp. 036119812110200
Author(s):  
Christopher Cummings ◽  
Hani Mahmassani
Keyword(s):  
Traffic Flow ◽  
Flow Characteristics ◽  
Urban Air ◽  
Traffic Flows ◽  
Traffic Patterns ◽  
Fundamental Diagram ◽  
Exhaustible Resource ◽  
Urban Streets ◽  
Macroscopic Fundamental Diagram ◽  
Resolution Scheme

Urban air mobility (UAM) is an emerging mode that promises to provide relief to congested urban streets. UAM relies on airspace, however, which is an exhaustible resource considering minimum aircraft separation requirements. In light of these requirements and UAM vehicle attributes, a simulation is developed to explore UAM traffic flows and congestion development. A decentralized conflict resolution scheme is employed in the form of a non-linear program (NLP) to offer improved flexibility in detours relative to past aircraft simulations. An expansion of Edie’s definitions of density and flow rate are used in conjunction with average speed to explore the relationships between traffic flow characteristics. The results find that UAM traffic flows emulate those of other modes, by following the familiar traffic patterns of build-up and breakdown captured in the macroscopic fundamental diagram. These findings also suggest the presence of a capacity of airspace that should be carefully managed by operators to achieve optimal system performance. The relationships established in this study highlight issues that UAM operators and aviation planners may face and could be used to improve the vehicle traffic modeling of other UAM models.

Recent developments in traffic flow modeling using macroscopic fundamental diagram

2020 ◽  
Vol 40 (4) ◽  
pp. 529-550
Author(s):  
Lele Zhang ◽  
Zhongqi Yuan ◽  
Li Yang ◽  
Zhiyuan Liu
Keyword(s):  
Traffic Flow ◽  
Flow Modeling ◽  
Fundamental Diagram ◽  
Macroscopic Fundamental Diagram ◽  
Recent Developments

MODIFIED COMFORTABLE DRIVING MODEL FOR CONGESTED TRAFFIC FLOW

2004 ◽  
Vol 18 (14) ◽  
pp. 1991-2001 ◽  
Author(s):  
RUI JIANG ◽  
QING-SONG WU
Keyword(s):  
Time Series ◽  
Computer Simulation ◽  
Traffic Flow ◽  
Red Light ◽  
Flow Density ◽  
Traffic Patterns ◽  
Fundamental Diagram ◽  
Average Data ◽  
Congested Traffic ◽  
Driving Model

In this paper, the concepts of "jammed status" and "jam headway" [X. B. Li, R. Jiang and Q. S. Wu, Phys. Rev.E68, 016117 (2003)] are introduced into the Modified Comfortable Driving (MCD) model [R. Jiang and Q. S. Wu, J. Phys.A36, 381 (2003)] to simulate the congested traffic flow including synchronized flow and wide moving jams. Using computer simulation, the fundamental diagram, the space–time plots, the time series of the density in the jams, the 1-min average data in the flow-density plane, the traffic patterns induced by red light are investigated. It is shown that the new model can describe both the synchronized flow and the sparse wide jams quite well.

scholarly journals Impact of Road Bends on Traffic Flow in a Single-Lane Traffic System

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Zeng Junwei ◽  
Qian Yongsheng ◽  
Xu Dejie ◽  
Jia Zhilong ◽  
Huang Zhidan
Keyword(s):  
Traffic Flow ◽  
Peak Flow ◽  
Inhibitory Effect ◽  
Arc Length ◽  
Traffic Flows ◽  
Bend Radius ◽  
Fundamental Diagram ◽  
Traffic System ◽  
Inhibition Effect ◽  
Road Friction

Taking the characteristics of road bends as a research object, this work proposes the cellular model (CA) with road bends based on the NaSch model, with which the traffic flow is examined under different conditions, such as bend radius, bend arc length, and road friction coefficiency. The simulation results show that, with the increase of the bend radius, the peak flow will be continuously increased, and the fundamental diagram will become more similar to that of the classic NaSch model; the smaller the bend radius is, the easier it is for the occurrence of blockage; for different bend lengths, all the corresponding traffic flows show that the phenomenon of go-and-stop and the bends exert slight inhibitory effect on traffic flow; under the same bend radius, the inhibition effect of the bends on the traffic flow will be weakened with the increase of the friction coefficiency.

scholarly journals Application of Macroscopic Fundamental Diagram under Flooding Situation to Traffic Management Measures

2021 ◽  
Vol 13 (20) ◽  
pp. 11227
Author(s):  
Piyapong Suwanno ◽  
Rattanaporn Kasemsri ◽  
Kaifeng Duan ◽  
Atsushi Fukuda
Keyword(s):  
Traffic Flow ◽  
Traffic Management ◽  
Road Network ◽  
Road Traffic ◽  
Control Measures ◽  
Flow Density ◽  
Fundamental Diagram ◽  
Urban Flood ◽  
Traffic Conditions ◽  
Macroscopic Fundamental Diagram

Bangkok, Thailand is prone to flooding after heavy rain. Many road sections become impassable, causing severe traffic congestion and greatly impacting activities. Optimal vehicle management requires the knowledge of flooding impact on road traffic conditions in specific areas. A method is proposed to quantify urban flood situations by expressing traffic conditions in specific ranges using the concept of macroscopic fundamental diagram (MFD). MFD-based judgement allows for a road manager to understand the current traffic situation and take appropriate traffic control measures. MFD analysis identified traffic flow–density and density–velocity relationships by using the shape of the estimated MFD travel time-series plots. Then, results were applied to develop a traffic model with vehicle-flow parameters as a measuring method for road-network performance. The developed model improved road-network traffic-flow performance under different flood conditions. A method is also presented for traffic management evaluation on the assumption that flooding occurs.

scholarly journals Estimation of Hourly Traffic Flows from Floating Car Data for Vehicle Emission Estimation

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Yun Jiang ◽  
Guohua Song ◽  
Zeyu Zhang ◽  
Zhiqiang Zhai ◽  
Lei Yu
Keyword(s):  
Traffic Flow ◽  
Traffic Flows ◽  
Fundamental Diagram ◽  
Flow Estimation ◽  
Floating Car Data ◽  
Estimation Uncertainty ◽  
Spatial And Temporal Distributions ◽  
Significant Difference ◽  
Traffic Flow Estimation ◽  
Hysteresis Phenomena

In order to model air quality in heavy pollution days, a dynamic emission monitoring system is implemented in the Beijing road network, which requires the input of hourly traffic flows. Floating car data (FCD) is increasingly employed for flow estimation based on the fundamental diagrams to supplement data provided by stationary detectors. However, existing studies often used a typical fundamental diagram without considering the hysteresis phenomena and the uncertainty of traffic flow estimation. This study aims to develop a multiperiod fundamental diagram for the traffic flow estimation from FCD considering the hysteresis phenomena. The result shows that the proposed multiperiod fundamental diagram can improve the accuracy of flow estimation. The uncertainty of traffic flow estimation at both 10 minutes and 1 hour is also quantified, and the result indicates that the variation of the estimation uncertainty at 1 hour is lower than that at 10 minutes, with an average 7% reduction of the range of 95% confidence interval (CI). But there is no significant difference in magnitudes of the estimation uncertainty at 1 hour compared with that at 10 minutes. Moreover, the uncertainty for congested flows is lower than that for free flows. In the case study, the proposed model is employed to develop the spatial and temporal distributions of flows and emissions for the metropolitan area in Beijing.

scholarly journals Appraisal of Busy Traffic Intersections and Design of Coordinated Signal System

2020 ◽  
Vol 8 (5) ◽  
pp. 1105-1109 ◽  
Keyword(s):  
Traffic Flow ◽  
Urban Areas ◽  
Flow Characteristics ◽  
Traffic Signals ◽  
Simulation Software ◽  
Traffic Flows ◽  
Travel Times ◽  
Traffic Intersections ◽  
In Series ◽  
Road Intersections

Road intersections in series in urban areas lead to discord between opposing traffic flows and cause delays and accidents. To overcome these problems at intersections, the traffic flows across the intersections are controlled by using signals. The fixed timings and isolated operation of signals at each intersection along a street may cause delays on red duration and generate vehicular queue during peak hours. Proper timing and coordination of the signal timings with reference to intersection distance and the average travelling speed of vehicles can boost traffic handling capacity along the streets during busiest hours. This work has been conducted to assess the current operating system of traffic signals and investigate the benefits of these signals coordinatedby using micro-simulation software PTV VISSIM. Initially, the VISSIM simulation was calibrated and the coordinated signals were run for execution based on the prepared model in VISSIM. The traffic flow delays and travel times obtained by the simulation were compared with the corresponding values before coordination. A considerable decrease in delays and travel times was noticed after coordinating the signals along the study street. It is also useful for similar traffic coordination studies elsewhere, subjected to the intervals of intersections and traffic flow characteristics are comparable.

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